1 files changed, 323 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/util/ParsableBitArray.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/util/ParsableBitArray.java
new file mode 100644
index 0000000000..3d6a702723
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/util/ParsableBitArray.java
@@ -0,0 +1,323 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.mozilla.thirdparty.com.google.android.exoplayer2.util;
+
+/**
+ * Wraps a byte array, providing methods that allow it to be read as a bitstream.
+ */
+public final class ParsableBitArray {
+
+  public byte[] data;
+
+  // The offset within the data, stored as the current byte offset, and the bit offset within that
+  // byte (from 0 to 7).
+  private int byteOffset;
+  private int bitOffset;
+  private int byteLimit;
+
+  /** Creates a new instance that initially has no backing data. */
+  public ParsableBitArray() {
+    data = Util.EMPTY_BYTE_ARRAY;
+  }
+
+  /**
+   * Creates a new instance that wraps an existing array.
+   *
+   * @param data The data to wrap.
+   */
+  public ParsableBitArray(byte[] data) {
+    this(data, data.length);
+  }
+
+  /**
+   * Creates a new instance that wraps an existing array.
+   *
+   * @param data The data to wrap.
+   * @param limit The limit in bytes.
+   */
+  public ParsableBitArray(byte[] data, int limit) {
+    this.data = data;
+    byteLimit = limit;
+  }
+
+  /**
+   * Updates the instance to wrap {@code data}, and resets the position to zero.
+   *
+   * @param data The array to wrap.
+   */
+  public void reset(byte[] data) {
+    reset(data, data.length);
+  }
+
+  /**
+   * Sets this instance's data, position and limit to match the provided {@code parsableByteArray}.
+   * Any modifications to the underlying data array will be visible in both instances
+   *
+   * @param parsableByteArray The {@link ParsableByteArray}.
+   */
+  public void reset(ParsableByteArray parsableByteArray) {
+    reset(parsableByteArray.data, parsableByteArray.limit());
+    setPosition(parsableByteArray.getPosition() * 8);
+  }
+
+  /**
+   * Updates the instance to wrap {@code data}, and resets the position to zero.
+   *
+   * @param data The array to wrap.
+   * @param limit The limit in bytes.
+   */
+  public void reset(byte[] data, int limit) {
+    this.data = data;
+    byteOffset = 0;
+    bitOffset = 0;
+    byteLimit = limit;
+  }
+
+  /**
+   * Returns the number of bits yet to be read.
+   */
+  public int bitsLeft() {
+    return (byteLimit - byteOffset) * 8 - bitOffset;
+  }
+
+  /**
+   * Returns the current bit offset.
+   */
+  public int getPosition() {
+    return byteOffset * 8 + bitOffset;
+  }
+
+  /**
+   * Returns the current byte offset. Must only be called when the position is byte aligned.
+   *
+   * @throws IllegalStateException If the position isn't byte aligned.
+   */
+  public int getBytePosition() {
+    Assertions.checkState(bitOffset == 0);
+    return byteOffset;
+  }
+
+  /**
+   * Sets the current bit offset.
+   *
+   * @param position The position to set.
+   */
+  public void setPosition(int position) {
+    byteOffset = position / 8;
+    bitOffset = position - (byteOffset * 8);
+    assertValidOffset();
+  }
+
+  /**
+   * Skips a single bit.
+   */
+  public void skipBit() {
+    if (++bitOffset == 8) {
+      bitOffset = 0;
+      byteOffset++;
+    }
+    assertValidOffset();
+  }
+
+  /**
+   * Skips bits and moves current reading position forward.
+   *
+   * @param numBits The number of bits to skip.
+   */
+  public void skipBits(int numBits) {
+    int numBytes = numBits / 8;
+    byteOffset += numBytes;
+    bitOffset += numBits - (numBytes * 8);
+    if (bitOffset > 7) {
+      byteOffset++;
+      bitOffset -= 8;
+    }
+    assertValidOffset();
+  }
+
+  /**
+   * Reads a single bit.
+   *
+   * @return Whether the bit is set.
+   */
+  public boolean readBit() {
+    boolean returnValue = (data[byteOffset] & (0x80 >> bitOffset)) != 0;
+    skipBit();
+    return returnValue;
+  }
+
+  /**
+   * Reads up to 32 bits.
+   *
+   * @param numBits The number of bits to read.
+   * @return An integer whose bottom {@code numBits} bits hold the read data.
+   */
+  public int readBits(int numBits) {
+    if (numBits == 0) {
+      return 0;
+    }
+    int returnValue = 0;
+    bitOffset += numBits;
+    while (bitOffset > 8) {
+      bitOffset -= 8;
+      returnValue |= (data[byteOffset++] & 0xFF) << bitOffset;
+    }
+    returnValue |= (data[byteOffset] & 0xFF) >> (8 - bitOffset);
+    returnValue &= 0xFFFFFFFF >>> (32 - numBits);
+    if (bitOffset == 8) {
+      bitOffset = 0;
+      byteOffset++;
+    }
+    assertValidOffset();
+    return returnValue;
+  }
+
+  /**
+   * Reads up to 64 bits.
+   *
+   * @param numBits The number of bits to read.
+   * @return A long whose bottom {@code numBits} bits hold the read data.
+   */
+  public long readBitsToLong(int numBits) {
+    if (numBits <= 32) {
+      return Util.toUnsignedLong(readBits(numBits));
+    }
+    return Util.toLong(readBits(numBits - 32), readBits(32));
+  }
+
+  /**
+   * Reads {@code numBits} bits into {@code buffer}.
+   *
+   * @param buffer The array into which the read data should be written. The trailing {@code numBits
+   *     % 8} bits are written into the most significant bits of the last modified {@code buffer}
+   *     byte. The remaining ones are unmodified.
+   * @param offset The offset in {@code buffer} at which the read data should be written.
+   * @param numBits The number of bits to read.
+   */
+  public void readBits(byte[] buffer, int offset, int numBits) {
+    // Whole bytes.
+    int to = offset + (numBits >> 3) /* numBits / 8 */;
+    for (int i = offset; i < to; i++) {
+      buffer[i] = (byte) (data[byteOffset++] << bitOffset);
+      buffer[i] = (byte) (buffer[i] | ((data[byteOffset] & 0xFF) >> (8 - bitOffset)));
+    }
+    // Trailing bits.
+    int bitsLeft = numBits & 7 /* numBits % 8 */;
+    if (bitsLeft == 0) {
+      return;
+    }
+    // Set bits that are going to be overwritten to 0.
+    buffer[to] = (byte) (buffer[to] & (0xFF >> bitsLeft));
+    if (bitOffset + bitsLeft > 8) {
+      // We read the rest of data[byteOffset] and increase byteOffset.
+      buffer[to] = (byte) (buffer[to] | ((data[byteOffset++] & 0xFF) << bitOffset));
+      bitOffset -= 8;
+    }
+    bitOffset += bitsLeft;
+    int lastDataByteTrailingBits = (data[byteOffset] & 0xFF) >> (8 - bitOffset);
+    buffer[to] |= (byte) (lastDataByteTrailingBits << (8 - bitsLeft));
+    if (bitOffset == 8) {
+      bitOffset = 0;
+      byteOffset++;
+    }
+    assertValidOffset();
+  }
+
+  /**
+   * Aligns the position to the next byte boundary. Does nothing if the position is already aligned.
+   */
+  public void byteAlign() {
+    if (bitOffset == 0) {
+      return;
+    }
+    bitOffset = 0;
+    byteOffset++;
+    assertValidOffset();
+  }
+
+  /**
+   * Reads the next {@code length} bytes into {@code buffer}. Must only be called when the position
+   * is byte aligned.
+   *
+   * @see System#arraycopy(Object, int, Object, int, int)
+   * @param buffer The array into which the read data should be written.
+   * @param offset The offset in {@code buffer} at which the read data should be written.
+   * @param length The number of bytes to read.
+   * @throws IllegalStateException If the position isn't byte aligned.
+   */
+  public void readBytes(byte[] buffer, int offset, int length) {
+    Assertions.checkState(bitOffset == 0);
+    System.arraycopy(data, byteOffset, buffer, offset, length);
+    byteOffset += length;
+    assertValidOffset();
+  }
+
+  /**
+   * Skips the next {@code length} bytes. Must only be called when the position is byte aligned.
+   *
+   * @param length The number of bytes to read.
+   * @throws IllegalStateException If the position isn't byte aligned.
+   */
+  public void skipBytes(int length) {
+    Assertions.checkState(bitOffset == 0);
+    byteOffset += length;
+    assertValidOffset();
+  }
+
+  /**
+   * Overwrites {@code numBits} from this array using the {@code numBits} least significant bits
+   * from {@code value}. Bits are written in order from most significant to least significant. The
+   * read position is advanced by {@code numBits}.
+   *
+   * @param value The integer whose {@code numBits} least significant bits are written into {@link
+   *     #data}.
+   * @param numBits The number of bits to write.
+   */
+  public void putInt(int value, int numBits) {
+    int remainingBitsToRead = numBits;
+    if (numBits < 32) {
+      value &= (1 << numBits) - 1;
+    }
+    int firstByteReadSize = Math.min(8 - bitOffset, numBits);
+    int firstByteRightPaddingSize = 8 - bitOffset - firstByteReadSize;
+    int firstByteBitmask = (0xFF00 >> bitOffset) | ((1 << firstByteRightPaddingSize) - 1);
+    data[byteOffset] = (byte) (data[byteOffset] & firstByteBitmask);
+    int firstByteInputBits = value >>> (numBits - firstByteReadSize);
+    data[byteOffset] =
+        (byte) (data[byteOffset] | (firstByteInputBits << firstByteRightPaddingSize));
+    remainingBitsToRead -= firstByteReadSize;
+    int currentByteIndex = byteOffset + 1;
+    while (remainingBitsToRead > 8) {
+      data[currentByteIndex++] = (byte) (value >>> (remainingBitsToRead - 8));
+      remainingBitsToRead -= 8;
+    }
+    int lastByteRightPaddingSize = 8 - remainingBitsToRead;
+    data[currentByteIndex] =
+        (byte) (data[currentByteIndex] & ((1 << lastByteRightPaddingSize) - 1));
+    int lastByteInput = value & ((1 << remainingBitsToRead) - 1);
+    data[currentByteIndex] =
+        (byte) (data[currentByteIndex] | (lastByteInput << lastByteRightPaddingSize));
+    skipBits(numBits);
+    assertValidOffset();
+  }
+
+  private void assertValidOffset() {
+    // It is fine for position to be at the end of the array, but no further.
+    Assertions.checkState(byteOffset >= 0
+        && (byteOffset < byteLimit || (byteOffset == byteLimit && bitOffset == 0)));
+  }
+
+}